Phycological Research 2009; 57: 12–24 Four new species of Rhodophyceae from Fiji, Polynesia and Vanuatu, South Pacific Antoine D. R. N’Yeurt1* and Claude E. Payri1,2 1 UMR 7138 ‘Systématique, Adaptation, Evolution’, Institut de Recherche Pour le Développement-Nouméa, B.P. A5 98848 Nouméa Cedex New Caledonia, and 2Université de la Polynésie Française B.P. 6570 Faa’a Tahiti 98702, French Polynesia SUMMARY Four new species of Rhodophyceae are described from the South Pacific, with type localities in Fiji, French Polynesia and Vanuatu. Chondria bullata from the Tuamotus (French Polynesia), Vanuatu, Palmerston Atoll (Cook Islands) and Fiji is unique owing to its nonconstricted axes with markedly protruding, bubble-like cortical cells. Halymenia nukuhivensis, from the Marquesas Islands in French Polynesia, is distinguished from others in the genus by its dichotomous, papery blades issued from a strap-shaped basal region, and the equal proportion of anti-clinal, periclinal and oblique filaments in its medullary layer. Jania articulata, so far known only from the Tuamotus in French Polynesia and Manihiki in the Northern Cook Islands, superficially resembles the genus Amphiroa with its articulated branches with numerous genicula between successive dichotomies, and its large axis diameter. Meristotheca peltata from the Fiji Islands is unique among the genus by its distinctly peltate, erect habit. The recent high number of newly described species from the South Pacific region emphasizes the need for more in-depth surveys, particularly in deeper outer reef slope habitats, which remain for the most part unexplored and could yield particularly interesting new taxa or distributional records. Key words: Chondria bullata, Halymenia nukuhivensis, Jania articulata, Meristotheca peltata, new species, Rhodophyceae, South Pacific, taxonomy. INTRODUCTION The South Pacific region (Fig. 1) encompasses a vast geographic area, between the Australian and South American continents into which there are widely scattered numerous archipelagoes with a wide range of habitats, from high volcanic islands to low-lying coral atolls. The phycological collecting effort in this region has been relatively sporadic and limited, with historical peaks in the later half of the nineteenth century (e.g. Harvey 1857; Grunow 1874; Weber-van Bosse 1898) and early and mid twentieth century (e.g. Børgesen 1924; Setchell 1924, 1926; Taylor 1950; Dawson 1956, 1957). In more recent times, with the widespread use of scuba diving and the advent of systematic regional biodiversity surveys, more data on algal diversity and distribution have been obtained for South Pacific localities (e.g. N’Yeurt 1996, 2001; Abbott 1999a,b; Payri et al. 2000, 2004; Littler & Littler 2003; South & Skelton 2003; N’Yeurt & Payri 2004; 2006, 2007; Millar & Payri 2006; Payri 2006; N’Yeurt et al. 2007; Skelton & South 2007). Despite this apparent surge in phycological effort, considering the vastness of the geographic area in question and the diversity of biotopes available, most localities still remain largely unexplored, especially for deeper water flora. In the context of ongoing surveys of regional floras from the South Pacific, four new species of marine Rhodophyceae are reported in the present study. MATERIALS AND METHODS Plants were collected by scuba diving or reef-walking, and stored in 5% buffered formalin. Sections were made using a freezing microtome, and stained using either cotton blue/lactophenol or 1% aniline blue in 60% clear corn syrup. Prepared slides were examined using a camera-lucida mounted on an Olympus BH-2 microscope (Olympus Optical Co. Ltd, Tokyo, Japan). Macrophotographs were taken with an Olympus SZ-40 stereomicroscope fitted with an Olympus PM-10 ADS camera unit and Olympus PM-CBSP exposure unit, printed on Kodak Plus-X pan 125 film, developed and printed in the laboratory. Microphotographs were taken with an Olympus C-5050 digital camera and the resulting files processed into figures using computer software. Voucher specimens have been deposited in the *To whom correspondence should be addressed. Email: nyeurt@gmail.com Communicating editor: J. West. Received 22 January 2007; accepted 9 July 2008. doi: 10.1111/j.1440-1835.2008.00517.x © 2009 Japanese Society of Phycology New Rhodophyceae from the South Pacific Fig. 1. 13 Map of the South Pacific, including collecting localities. herbaria of the Université de la Polynésie Française in Tahiti (UPF), Institut de Recherche Pour le Développement (IRD) (Nouméa, New Caledonia), Suva, Fiji (SUVA-A). Accession numbers followed by the letter ‘L’ indicate liquid-preserved material, while those preceded by the letter ‘S’ refer to microscope slide collections. Herbarium acronyms follow Holmgren et al. (1990). RESULTS AND DISCUSSION Halymeniales G.W. Saunders et Kraft Halymeniaceae Kützing Halymenia C. Agardh, nomen conservandum *Halymenia nukuhivensis N’Yeurt et Payri, sp. nov. (Figs 2–6) Description. Thallus 50–60 mm altus. Portio thalli irregulariter ligulata, 3–5 mm lata, e qua fasiculi 8–10 laminarum tenuissimarum velut charta atque cuneatarum usque ad spathulatarum emanantes. Laminae 5–15 mm latae et 120–130 mm crassae, ramosae lateraliter atque late dichotomeque. Cortex stratus 2–3plo. Cellulae extimae corticales cuboideae usque ad leniter elongatae, 2.5–6.0 mm diametro et 2.0–6.0 mm longae, binatae portata in cellulis rotundis 4–5 mm diametro. Cellulae intimae corticales ovoideae usque ad stellatae, 10–20 mm diametro atque plerumque © 2009 Japanese Society of Phycology bracchiis gracilibus filamenta medullosa 5–7 mm diametro et 15–40 mm longa subtentes. Medulla e filamentis anti-clinalibus, periclinalibus et obliquis, in proportionibus aequalibus, constans. Thallus 50–60 mm high, composed of an irregular, strap-shaped portion of thallus 3–5 mm wide, from which are issued clusters of 8–10 papery-thin cuneate to spathulate blades 5–15 mm broad and 120–130 mm thick, irregularly and broadly dichotomously branched. Attachment to the substratum is via a small stipe about 2 mm long and 0.5–1.0 mm in diameter (Fig. 2), slightly thicker but of similar internal anatomy to the rest of the thallus. Color in living state is unknown; formalin-preserved material is yellow-cream becoming brownish-black in basal portions. Cortex 2–3 layered; outermost cortical cells cuboid to slightly elongate, 2.5–6.0 mm in diameter and 2.0– 6.0 mm long, borne in pairs on rounded cells 4–5 mm in diameter (Fig. 4). Innermost cortical cells ovoid, refractive, ganglionic to stellate, 10–20 mm in diameter, usually with three to six slender arms subtending medullary filaments 5–7 mm in diameter and 15–40 mm long (Fig. 5). Medulla composed in almost equal proportions of periclinal, anti-clinal and oblique filaments (Figs 3,4). Carpogonial branches were not seen. Auxiliary cells are formed in open ampullar baskets, with branched filaments lining a narrow neck (Fig. 6). Gonimoblasts 14 A. D. R. N’Yeurt and C. E. Payri Figs 2–6. Halymenia nukuhivensis sp. nov. vegetative and reproductive morphology of Holotype (UPF 575). 2. Habit of pressed plant, showing strap-shaped basal region (arrow). 3. Cross section showing dense cortex and presence of periclinal filaments (arrows) mixed with anti-clinal and oblique filaments. 4. Another section of the thallus, showing equally abundant presence of anti-clinal filaments (arrow) and cuboid cortical cells. 5. Region of inner cortex showing refractive ganglionic stellate cells (arrows). 6. Ampullar basket of female plant showing narrow ostiole (o) and gonimoblast initials issued from the auxiliary cell (arrow). develop on the auxiliary cell, after contact with a connecting filament, consisting of several successively maturing gonimolobes 10–15 mm in diameter surrounded by a lax involucre of sterile filaments, located in the outer medulla below a carpostome flanked by elongate sterile cells. Plants do not adhere well to paper when dry. Holotype. Nuku Hiva (08°52′57′′S, 140°06′05′′W), Marquesas c. 1997, leg. J. Orempuller, UPF 575. Paratype. Nuku Hiva, Marquesas, c. 1997, leg. J. Orempuller, UPF 574. Etymology. the specific epithet is derived from the island of Nuku-Hiva, where the alga was first collected. Habitat. Growing subtidally, at about 20 m depth on rocky slopes. Distribution. Nuku-Hiva, Marquesas, French Polynesia. Remarks. The genus Halymenia currently consists of 66 species (Guiry & Guiry 2008). Abbott (1999a) recently surveyed known southwestern Pacific species of the genus Halymenia, but no mention was made of any taxon approaching the unusual habit of H. nukuhivensis. Among related foliose Pacific and tropical Halymenia species (Table 1), H. nukuhivensis sets itself apart by its strap-shaped basal portion from which are issued cuneate or irregularly subdichotomous blades, in contrast to the mostly simple, lobed habits of other species. It is also characterized by its dense, palisade-like outer cortex and the mostly equal proportion of anti-clinal, periclinal and oblique medullary filaments, which is unusual among the genus Halymenia where anti-clinal filaments are usually dominant. Its female reproductive features, such as open ampullary basket and slight involucre around the developing carposporophyte, fall well within the genus. Superficially, the cuneate, often irregularly subdichotomous habit could be mistaken for a species of Rhodymenia Greville, but its internal anatomy agrees well with the © 2009 Japanese Society of Phycology New Rhodophyceae from the South Pacific Table 1. 15 Comparison of selected characters between Halymenia nukuhivensis and other related species Species Habit and texture Cortical cells Medullary filaments H. nukuhivensis† Spathulate to cuneate or subdichotomous, issued from a strap-shaped base, papery; absence of a terete stipe Lobed clustered blades; gelatinous Cuboid to slightly elongate, in a palisade layer Equally periclinal, anti-clinal and oblique, 5–7 mm in diameter Ovoid, irregularly disposed Mostly anti-clinal, to 5 mm in diameter Foliose blade with a reniform or subpeltate base; stipe absent to short and thick Broadly lanceolate to subcordate, lobed, crisp to undulate; stipe small. Foliose, irregularly palmate to cuneate, or subdichotomously branched; fleshy and slippery; stipe solid, long and cylindrical, to 13 mm long Gelatinous, circular to elliptical, extremely thin and smooth, inconspicuous stalk Foliose, conspicuously stipitate blade; stalk cartilaginous, thick Rounded to elongate ‘rabbit eared’ Both periclinal and anti-clinal, 6–7 mm in diameter Ovoid, irregularly disposed Mostly anti-clinal, 4–10 mm in diameter Conspicuously elongate, ‘rabbit-eared’ Oblique or periclinal, occasionally anti-clinal, 4–5 mm in diameter Ovoid, mostly irregularly disposed Mostly anti-clinal, pillar-like and thick, to 10 mm in diameter Conspicuously elongate, ‘rabbit-eared’ Mostly periclinal, 5 mm in diameter H. actinophysa M. Howe (type locality: La Paz, Gulf of California)‡ H. dilatata Zanardini (type locality: Red Sea)§ H. hollenbergii I.A. Abbott (type locality: San Diego, California, USA)¶ H. maculata J. Agardh (type locality: Mauritius)†† H. porphyraeformis Parkinson (type locality: Okha, Gujarat, India)‡‡ H. stipitata I.A. Abbott (type locality: O’ahu, Hawaiian Islands)§§ Source: †This study; ‡Howe (1911); §Kawaguchi and Lewmanomont (1999); ¶Abbott (1967); ††Kawaguchi et al. (2002); ‡‡Parkinson (1980); §§Abbott (1998). genus Halymenia, notably the characteristic presence of anti-clinal filaments joining the upper and lower cortex, a character typical of the genus Halymenia (Abbott 1999b). So far in French Polynesia, H. nukuhivensis is only reported from the rocky slopes of the northern Marquesas group, an archipelago characterized by its submerged ancient reefs and lack of any typical barrier reefs (Cabioch et al. 2003; Montaggioni 2005). Corallinales P.C. Silva et H.W. Johansen Corallinaceae J.V. Lamouroux Jania J.V. Lamouroux *Jania articulata N’Yeurt et Payri, sp. nov. (Figs 7–15) Description. Thallus armeniacus usque ad eburinum, mollis et flexibilis, fasiculos usque ad 15 mm altos et 20–30 mm latos formans, e multis ramis articulatis constans. Rami articulati e segmentis calcifactis aut intergeniculis constantes. Calcificatio distincte annulata. Intergenicula nodis-non-calcifactis aut geniculis separata. Rami medulla filamentorum medullosorum quorum cellulae in stratis 40–50 mm distantibus ordi© 2009 Japanese Society of Phycology natae, cortice cellularum parvarum rotundatarum circumcinctae. Axes (200) 300–400 (600) mm diametro, geniculis frequentissimis et-non-calcifactis. Ramificatio dichotoma, aliquando trichotoma in partibus basalibus thallli. Intergenicula 400–1000 mm distantia. Genicula non ramosa 4–11 (22) inter dichotomis successivis. Apices ramorum rotundati,-non-inflati. Angulus ramificationis 45–60. Conceptacula tetrasporangiorum uni-locellata et tumida, in apicibus intergeniculorum terminalia, usque ad 500 mm lata et 400 mm alta, ramulis 2 superpositis. Tetrasporangia zonatim divisa, usque ad 200 mm longa et 80 mm diametro. Thallus reddish-orange to cream-colored, soft and pliable, forming clumps to 15 mm high and 20–30 mm wide (Fig. 7), consisting of numerous jointed branches composed of calcified segments or intergenicula; calcification distinctly annulate. Holdfast small and inconspicuous, embedded in coralline algae substratum. Intergenicula separated by uncalcified nodes or genicula (Figs 8–12); branches with a core of medullary filaments with cells organized in tiers 40–50 mm apart, surrounded by a cortex of small rounded cells. Axes (200) 300–400 (600) mm in diameter, with very fre- 16 A. D. R. N’Yeurt and C. E. Payri Figs 7–15. Jania articulata sp. nov. vegetative and reproductive morphology of Holotype (UPF 2710). 7. Habit of pressed plant, showing distinct annulate nature of branches. 8. Detail of decalcified branch node, showing slightly offset dichotomies and genicula (arrowheads). 9. View of decalcified fertile branch node, showing swollen, terminal tetrasporangial conceptacle with a narrow ostiole (arrow). 10. View of decalcified terminal axis, showing large number of unbranched genicula (arrowheads) between dicho- tomies. 11. Detail of rounded branch apex. 12. Detail of lower portion of axis, showing dichotomous branching. 13. Longitudinal section of decalcified genicula, showing densely packed elongate cells (g) and an intergenicular tier of cells (t, between arrows). 14. View of decalcified thallus surface, showing rounded cortical cells. 15. Transverse section of cortex, showing columnar subcortical cell (arrow). © 2009 Japanese Society of Phycology New Rhodophyceae from the South Pacific 17 Table 2. Comparison of selected characters between Jania articulata and other related species Species Branching Mid axis diameter (mm) Calcification Angle of branching (°) J. articulata† Dichotomous, at times trichotomous Dichotomous 300–400 Annulate 45–60 400–1000 1.3–2.5 (4) 11 (22) 70–140 Continuous 40–50 900–1200 8.5–12.9 2 Dichotomous 70–80 Continuous 30–40 500–800 7.1–10.0 3–4 Dichotomous 80–90 Continuous 80–90 400–600 5.0–6.7 5–10 Dichotomous 150–250 Continuous <30 1500–3500 10.0–14.0 J. adhaerens J.V. Lamouroux‡ J. pumila J.V. Lamouroux‡ J. rubens (Linnaeus) J.V. Lamouroux§ J. verrucosa ‡ Intergenicular distance (mm) Intergenicular length: width ratio No. unbranched genicula between successive dichotomies 1–5 Source: †This study; ‡Abbott (1999b), §N’Yeurt (1996). quent uncalcified genicula (Fig. 10). Branching dichotomous, sometimes trichotomous in basal portions of thallus; dichotomies slightly offset. Intergenicular distance 400–1000 mm; genicula numerous; between 4 and 11 (22) unbranched genicula between successive dichotomies. Intergenicular length: width ratio small, between 1.3 and 2.5. Intergenicula with (4) 6–11 (13) tiers of clear cylindrical cells 150–160 mm long and 5–6 mm in diameter; genicula composed of a single tier of densely packed elongate cylindrical cells 400–420 mm long and 5–6 mm in diameter (Fig. 13). Cortical cells (6)8–10(12) mm in diameter (Fig. 14), supported by elongate, cylindrical subcortical cells 25–30 mm long (Fig. 15). Branch apices rounded, not inflated, 150–200 mm in diameter (Fig. 11). Angle of branching 45–60°. Tetrasporangial conceptacles single-chambered and swollen, terminal on intergenicular apices, to 500 mm wide and 400 mm high, with two surmounting branchlets (Fig. 9). Tetrasporangia zonately divided, to 200 mm long and 80 mm in diameter. Holotype. Fangatau Atoll (15°49′50′′S, 140°54′00′′W), Tuamotu, 17 May 2003, leg. C. E. Payri, UPF 2710. Other material examined. Motu Tauhunu, Manihiki, Northern Cook Islands, 15 July 1974, leg. G. N. MacRaild, WELT CI25. Etymology. The specific epithet is derived from the L. articulatus, meaning jointed, referring to the numerous, distinctive flexible genicula of the new species. Habitat. Growing on the outer reef flat, epiphytic on coralline algae. Distribution. Tuamotu archipelago, French Polynesia and Manihiki, Northern Cook Islands. © 2009 Japanese Society of Phycology Remarks. The genus Jania consists of 35 current species worldwide (Guiry & Guiry 2008) and is characterized by its dichotomous branching and axial conceptacles (Womersley 1996). The large branch diameter and numerous interdichotomal genicula are distinctive characters of J. articulata within the genus Jania. From Table 2 showing some common tropical Pacific species of Jania, J. articulata has a much larger mid-axis diameter than other related species in the genus; also it sets itself apart by the very large number of unbranched genicula (up to 22) between successive intergenicular dichotomies, imparting the distinctive soft, pliable texture. The intergenicular length: width ratio of J. articulata is also by far the smallest among the reported species. A further difference is its sometime trichotomous branching, not reported in other Jania species. Jania articulata may superficially resemble some species of Amphiroa, but in the latter genus branching is irregularly dichotomous, axes are more than 1000 mm wide, and the reproductive structures are invariably borne on the intergenicular surfaces, whereas in Jania they occur in single, swollen chambers terminal on intergenicular apices (Norris & Johansen 1981). Gigartinales Schmitz Solieriaceae J. Agardh Meristotheca J. Agardh Meristotheca peltata N’Yeurt et Payri, sp. nov. As Meristotheca sp. in N’Yeurt 2001: 795, figs 212– 216. (Figs 16–24) Description. Thallus peltatus, 20–30 mm diametro et 870–900 mm crassus, marginibus undulatis et vadose vel profunde dentatis, in substrato per stipitem prominentem centralem 5–7 mm longem et 3–4 mm diametro affixus; rubro-viridis, supra interdum maculata. Medulla ex filamentis rhizoideis 2–5 mm diametro foveas conjungentes secondarias numerosas habenti- 18 bus pro parte maxima constans. Cellulae corticales extimae ellipticae, 6–7 mm diametro; cellulae proxime subcorticales sphaericae vel ovoideae, 14–16 mm diametro, refractivae contento copioso amyli; cellulae A. D. R. N’Yeurt and C. E. Payri intimae magnae, stellatae, multinucleatae, 42–60 mm diametro, foveis conjungentibus secondariis abundis instructae, rhizoidea transverse perducentia efferentes. Ramus carpogonialis-non-observatus; cystocarpia © 2009 Japanese Society of Phycology New Rhodophyceae from the South Pacific 19 Meristotheca peltata sp. nov. vegetative and reproductive morphology. 16. Habit of liquid-preserved Holotype (SUVA-A 5407La), showing distinctive peltate habit, undulate cystocarpic margin and central peg-like holdfast. 17. Habit of Paratype (SUVA-A Figs 16–24. 5407Lb) showing deeply cleft margin and central holdfast (s). 18. Habit of spermatangial thallus (SUVA-A 5482L), showing peltate habit, central holdfast (s) and dentate margin (arrowhead). 19. Transverse section of thallus (SUVA-A 5407La) showing inner filamentous medulla (m) and outer pseudoparenchymatous cortical layers (c). showing stellate inner cortical cell (arrow). 20. Transverse section of thallus near margin (SUVA-A 5407Lb) 21. Detail of female thallus (SUVA-A 5407La) with spinose marginal cystocarps (arrows). 22. Transverse section of carposporophyte (SUVA-A 5407L), showing central placenta of fused gametophytic and gonimoblast cells (p), carposporangial mass (cp) and ostiole (o). 23. Surface view of thallus (SUVA-A 5407La) showing ovoid ostiole (o). 24. Detail of cortex of male plant (SUVA-A 5482L) showing terminal spermatangia (arrow). 䉳 matura 1–1.5 mm diametro, pericarpio denso ostiolato interdum spinifero, superficialia ad marginem, protrudentia. Carposporophytum 545–800 mm diametro, placenta centralis ex cellulis connatis gametophyticis gonimoblastisque constans strato superficie carposporangiorum ovoideorum 7–11 mm diametro obtecta. Spermatangia terminalia in cellulis corticalibus extimis, superficialia in nematheciis elevatis. Tetrasporangia-non-observata. Thallus peltate, 20–30 mm in diameter and 870– 900 mm thick, with edges ruffled and shallowly or deeply dentate, attached to the substratum from its lower surface via a prominent peg-like central holdfast 5–7 mm long and 3–4 mm in diameter; reddish green, sometimes blotchy on upper surface (Figs 16–18). Medulla consisting mostly of rhizoidal filaments 2–5 mm in diameter with numerous secondary pit connections (Fig. 19). Outer cortical cells elliptical, 6–7 mm in diameter; cells immediately below spherical to ovoid, 14–16 mm in diameter, refractive with much starch content; inner cortical cells large, stellate, multinucleate, 42–60 mm in diameter, with abundant secondary pit connections and issuing transversely traversing rhizoids (Fig. 20). Carpogonial branch not seen. Cystocarps 1.0–1.5 mm in diameter, often spinose (Fig. 21), with a dense ostiolate pericarp, protruding from the upper surface on special papillae issued from the thallus margins (Figs 22,23). Carposporophyte 545–800 mm in diameter, consisting of a central placenta of fused gametophytic and gonimoblast cells covered by a surface layer of outwardly directed ovoid carposporangia 7–11 mm in diameter (Fig. 22). Spermatangia terminal on outer cortical cells, superficial in raised nemathecia (Fig. 24). Tetrasporangia not seen. Holotype. Belcher Rocks, Suva Lagoon, Fiji (18°10′15″S, 178°31′10″E), 7 November 1994, leg. D. W. Keats, -20 m, SUVA-A 5407La (cystocarpic). Paratypes. Belcher Rocks, Suva Lagoon, Fiji, 7 November 1994, leg. D. W. Keats, -20 m, SUVA-A 5407Lb (cystocarpic); 5407Lc.; Belcher Rocks, Suva Lagoon, Fiji, 13 November 1999, leg. D. W. Keats & A. D. R. N’Yeurt, -25 m, SUVA-A 5482L (spermatangial). © 2009 Japanese Society of Phycology Etymology. The specific epithet is derived from the L. peltatus, meaning shield-like and attached by its lower surface, referring to the circular blade with a central stalk, so far unique among the genus. Habitat. Growing at a depth of 25–30 m, on coral debris in a biotope characterized by relatively cool waters, high turbidity and strong wave action, where a high diversity of unusual taxa was found including the red alga Pinnatiphycus menouana (N’Yeurt et al. 2006) and some yet undescribed Gracilaria species. The adequate collection of specimens was hindered by the notoriously rough conditions of the site (Belcher Rocks), which only allows safe boat access a few days each year, and only three fertile specimens were collected and examined over a span of 5 years. Distribution. So far only known from the island of Viti Levu, Fiji. Remarks. The family Solieriaceae belongs to the red algal order Gigartinales, and consists of genera that are multiaxial, with secondary pit connections between adjacent cells, and ostiolate cystocarps with a central fusion cell of sterile tissue surrounded by a surface layer of carposporangia. Inner cortical cells are usually stellate (Gabrielson & Kraft 1984). Characteristics of genera within the family were further delineated by Guimarães and Oliveira (1996) to include the presence or absence of interconnecting medullary filaments and nemathecial reproduction, and auxiliary cell complexes recognizable prior to, or after, diploidization. Womersley (1994) had proposed the merger of the Solieriaceae within the Areschougiaceae based on the priority of the latter name, but Fredericq et al. (1999) and Saunders et al. (2004) provided new molecular evidence for the reinstatement of the family Solieriaceae. Within the Solieriaceae, the only two flattened, blade-like members are the genera Euryomma Schmitz and Meristotheca. Euryomma platycarpa, the only species in the genus, has been reported from Sri Lanka (Kylin 1932), and mainly differs from Meristotheca by having embedded, non-papillate cystocarps with much denser enveloping 20 A. D. R. N’Yeurt and C. E. Payri Figs 25–32. Chondria bullata sp. nov. vegetative and reproductive morphology. 25. General habit (IRD 3792). 26. Apical region of branch (VU 731), showing terminal trichoblasts (arrowhead). 27. Side view of main axis in mid-portion (UPF 423), showing distinctly bullate cortical cells (arrow). 28. Apical region of thallus (UPF 423) showing bullate cortical cells (arrowheads) and apical pit with rudimentary trichoblast. 29. Transverse section of mid-thallus (IRD 3792) showing small central axial cell (a) surrounded by five larger pericentral cells (1–5). Pericentral cell 4 has detached itself slightly from the axial cell during the preparation. 30. Surface view of thallus (UPF 423) showing isodiametric to lenticular cortical cells. 31. Apical region of fertile branchlet (IRD 3792) showing immersed tetrasporangia (t). 32. Detail of tetrasporangia (t), showing lateral attachment point (arrow). 䉴 Table 3. A comparison of selected characters between Meristotheca peltata and related Meristotheca species Species Type locality Habit Holdfast(s) Margins Cystocarps M. peltata† Belcher Rocks, Suva, Fiji Peltate, erect Dentate, curled Marginal M. coacta Okamura‡ Kyushu, Japan; Taiwan Dentate or fimbriate Unknown M. papulosa (Montagne) J. Agardh§ M. procumbens Gabrielson et Kraft¶ Hodeida, Yemen, Red Sea Prostrate, imbricating blades Erect, blade-like Single, central, prominent Multiple, marginal Single basal disc Smooth or curled Marginal Lord Howe Is, Australia Prostrate, blade-like Multiple, marginal Smooth or curled Marginal Sources: †This study; ‡Okamura (1930), Faye et al. (2007); §Agardh (1872); ¶Gabrielson and Kraft (1984). tissue. The genus Meristotheca currently consists of 11 species (Faye et al. 2008), all irregularly flabellate or dichotomously branched. Meristotheca is characterized by the absence of interconnecting cells amongst medullary filaments, the occurrence of reproductive structures in nemathecia and cystocarps on papillae or marginal proliferations, and the absence of an auxiliary cell complex distinguishable prior to diploidization (Guimarães & Oliveira 1996). In the Asia-Pacific region, the genus is represented by M. coacta Okamura, M. imbricata Faye et Masuda and M. papulosa (Montagne) J. Agardh from Japan (Yoshida et al. 1995; Faye et al. 2007), and M. procumbens Gabrielson et Kraft from the South Pacific (Gabrielson & Kraft 1984; Payri et al. 2000; N’Yeurt 2001; Littler & Littler 2003); the latter species being part of the traditional diet of some Pacific Islanders (N’Yeurt 1995). The Fijian plant is placed within the genus Meristotheca based on the pseudoparenchymatous nature of the cortex, multi-axial structure of the thallus with stellate cells, medullary filaments lacking interconnecting cells, and carposporophytes with a central placenta of fused cells. From Table 3 showing flabellate Pacific species of the genus, M. peltata is unique in having a consistently peltate habit and a peg-like central holdfast, in all three specimens examined collected 5 years apart. It is closest to M. gigartinoides Joly et Ugadim (Joly et al. 1965) which also has a single holdfast and dentate margins, but the latter species is much larger, blade-like and has cystocarps scattered over the surface, with the holdfast in a lateral, inferior position. Older specimens of M. peltata have been observed to have deeply cleft margins, with some anastomoses among the overlapping tiers reminiscent of M. procumbens, but the latter species has multiple discrete holdfasts and a decumbent habit unlike M. peltata. Although this is a relatively uncommon plant with only a few specimens collected, the peltate habit of the species was found to be consistent, in young plants as well as in older, fertile thalli, and also between collections spanning some five years (1994–1999). The eventual discovery of tetrasporangial thalli with presumably zonate tetrasporangia would be decisive in the firm placement of the species within the Solieriaceae. Unfortunately, no material suitable for molecular analyses is available, and recent algal surveys from Fiji and elsewhere in the region have not turned up any new collections of this distinctive species. Ceramiales Oltmans Rhodomelaceae Areschoug nomen conservandum Chondria C. Agardh *Chondria bullata N’Yeurt et Payri, sp. nov. (Figs 25–32) Description. Thallus usque ad 30 mm longus, repens, teres et irregulariter ramosus. Axes primarii (400) 545–600 (720) mm diametro. Axes secondarii (280) 320–360 (384) mm diametro, basi-non-constricti, claviformes, apicibus truncatis. Trichoblasti apicales, aggregati 3–8, dichotome ramosi, 160–400 mm alti, e cellulis cylindricis 50–60 mm longis et 25–40 mm diametro constantes. Cellulae superficiares (28) 32–48 (56) mm diametro, isodiametrae usque ad lenticulares, valde protrudentes 5–16 mm per thallum, © 2009 Japanese Society of Phycology New Rhodophyceae from the South Pacific praesertim in partibus apicalibus iunioribus. Cellula axialis teres, 30–40 mm diametro, cellulis 5 pericentralibus elongatis usque ad ovoideis 70–80 mm diametro circumventa. Tetrasporangia in partibus © 2009 Japanese Society of Phycology 21 subapicalibus ramulorum fecundorum immersa, 50–120 mm diametro, tetraedice divisa atque lateraliter affixa ad cellulam parentis. Materia gametangialis ignota. Source: †This study; ‡Abbott (1999b), N’Yeurt (1996, 2001), Price and Scott (1992); §Børgesen (1924). Flush, polygonal to elliptical, 15–65 mm in diameter Slightly constricted Secund to alternate Terete, creeping (170) 300–410 (900) Flush, ovoid to elongate, 20–70 mm in diameter Irregular Terete, creeping 200–300 Markedly constricted, spindle-shaped axes Constricted Irregular 125–200 (500) Unconstricted Slightly constricted Terete, creeping Main axis diameter (mm) (400) 545–600 (720) 1000–2500 Irregular Subdistichous Remarks. A genus of some 74 current species worldwide (Guiry & Guiry 2008), Chondria in the tropical Pacific is represented by relatively few species, mostly diminutive and creeping or epiphytic (except for C. armata (Kützing) Okamura and C. ryukyuensis Yamada). Among related tropical species (Table 4), Chondria bullata is so far unusual in its markedly protruding cortical cells throughout its thallus and unconstricted secondary axes. Superficially similar to Chondria simpliciuscula, C. bullata is distinguished by its markedly projecting surface cells, which are not Terete, creeping Flattened, decumbent Distribution. Fiji, French Polynesia, Cook Islands, Vanuatu. Branching Habitat. Growing on coral debris, on reef slope. Habit Etymology. The specific epithet is derived from the L. ‘ebullio’, meaning to bubble-up, in reference to the characteristic exerted shape of the cortical cells, which look like bubbles in surface view. Species Other material examined. Palmerston Atoll, Cook Islands, 25 May 1974, leg. G.N. MacRaild, WELT CI439a. Table 4. Comparison of selected characters between Chondria bullata and other related species Paratypes. Abokisa Island, Santo, Vanuatu, 22 August 2006, -35 m, leg. C. E. Payri, Geoffray and J. L. Menou, VU 731; Malo Island, Santo, Vanuatu, 31 August 2006, -18 m, leg. C. E. Payri, Geoffray and J. L. Menou, IRD 3791; Nagelelevu Island, Fiji, 20 May 2007, leg. C. E. Payri, -20 m, IRD 2347, IRD 2348. Base of branches Holotype. Nihiru Atoll (16°41′60″S, 142°49′60″W), Tuamotu, French Polynesia, 01 October 1995, leg. J. Orempuller, UPF 423 S37, UPF 424 S38. C. bullata† C. dangeardii E.Y. Dawson‡ C. minutula Weber-van Bosse‡ C. repens Børgesen§ C. simpliciuscula Weber-van Bosse‡ Cortical cells Thallus to 30 mm long, creeping, terete and irregularly branched. Primary axes (400) 545–600 (720) mm in diameter; secondary axes (280) 320–360 (384) mm in diameter, unconstricted at the base, clavate shaped, with truncate apices (Fig. 25). Trichoblasts scarce, but when present terminal in groups of three to eight and dichotomously branched, 160–400 mm high, composed of cylindrical cells 50–60 mm long and 25–40 mm in diameter (Fig. 26). Axial cell terete, 30–40 mm in diameter, surrounded by five elongate to ovoid pericentral cells 70–80 mm in diameter (Fig. 29). Surface cells (28) 32–48 (56) mm in diameter, isodiametric to lenticular in shape (Fig. 30), markedly protruding by 5–16 mm throughout the thallus, especially in younger apical portions (Figs 27,28). Tetrasporangia immersed in subapical portions of fertile branchlets, 50–120 mm in diameter, tetrahedrally divided and laterally attached to parent cell (Figs 31,32). Gametangial material unknown. Flush, elongate to ellipsoidal, 12–25 mm in diameter A. D. R. N’Yeurt and C. E. Payri Protruding, isodiametric to lenticular, 30–40 mm in diameter Flush, elongate-cylindrical, 15–25 mm in diameter 22 © 2009 Japanese Society of Phycology New Rhodophyceae from the South Pacific elongated but isodiametric to lenticular in shape. Chondria simpliciuscula from the Great Barrier Reef (Price & Scott 1992) and Hawai’i (Abbott 1999b) differ slightly in their descriptions, but the Hawaiian material is deemed more typical, and certainly differs from C. bullata in a number of characters (Table 4). Chondria bullata differs from Chondria repens by its protruding, smaller diameter cortical cells and lack of constrictions at the base of branchlets. It is interesting to have recently identified C. bullata from hitherto unexamined collections in WELT from Palmerston Atoll in the central Cook Islands, thus bridging its distributional range from eastern Polynesia to western Melanesia. ACKNOWLEDGMENTS ADRN and CEP wish to thank the Coral Reef Initiative for the South Pacific (CRISP) program for financial support towards this study and CEP is grateful to the crew of the IRD oceanographic vessel ‘ALIS’ and the divers from IRD. ADRN is grateful to the University of the South Pacific and the New Zealand Government Overseas Development Agency (NZODA) for financial support during the earlier part of this research. Professor G. Robin South and the staff of the Marine Studies Program at the University of the South Pacific are thanked for logistical support in Fiji, especially Fiu Manueli, Suren Chand, Timoci Varinava and Sydney Malo for diving support. Dr R. E. Norris is thanked for examining specimens of M. peltata, as is Mr Gregory Lasne for photographs of the type material of H. nukuhivensis. Drs Jennifer Dalen and Wendy Nelson (Te Papa – WELT) are thanked for kindly organizing a visit to their herbarium to examine specimens from Polynesia. 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